| 摘要 |
A substantially entirely plastic rotary drum filter is made by applying a layer of plastic to the interior surface of a cylindrical mold, removing the mold, and applying at least one additional layer of plastic to the exposed exterior surface of the shell formed by the first layer. A plastic annular axial valve housing with plural valve chambers and a central valve receiving space is mounted to a head assembly at the head end of the shell. A tail assembly closes the opposite end of the shell to form the drum. Circumferentially spaced interior plastic bucket sections are positioned midway between the head and tail assemblies. Upon the periodic application of a vacuum to the valve chambers, filtrate is delivered from the exterior of the drum through an associated bucket and plastic drainage conduit to an associated valve chamber. Plastic reinforcing rings strengthen the drum along its length and in the region of the bucket section. In making the plastic annular valve housing, radially extending circumferentially spaced valve chamber side wall members are positioned about the axis of the valve receiving space. Dissolvable molds are inserted at least partially in the space between the members with an outwardly projecting valve chamber inlet defining neck portion. Plastic is applied to these molds and interconnects selected marginal edges of the side wall members so as to form the outer shell of the annular valve housing.
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